Context is important. In your case, you’re using female to designate a biological characteristic - aka, a reproductive ability that the cult is specifically exploiting. Some men, especially online, use “female” in a way where normally someone would use the term “woman”, in an attempt to dehumanize women. It’s unfortunate that the person you were talking to couldn’t tell the difference, but as for never forgiving them, maybe a gentle correction could be more warranted?